bfq scheduler. Performance accesing metadata is very poor and can hause system lockups.mkfs.btrfs is 16kB and offers best performance. If file is small enough to be stored in btrfs leaf metadata it is directly stored in metadatas (max file size if 16384-148 heaf header)Depending on your chosen Linux distribution, you might want to follow the latest 5.10 LTS kernel which is supposed to contain numerous btrfs related improvements. However, be warned that the current 5.10 kernel also has several btrfs related performance regression issues so definitely do not rush to upgrade even if you are capable of doing so.